Previous in vitro and in vivo studies have shown that an intraoral fluoride-releasing device developed by the Southern Research Institute for the National Institute of Dental Research will deliver fluoride at a steady rate for up to six months. This project will evaluate the anticaries effect and mechanism of action of the fluoride-releasing device in rats. Results have shown that rats that had an intraoral fluoride-releasing device in their mouth developed significantly fewer caries on all surfaces than untreated or placebo treated animals. The data indicate that the marked caries reduction produced by the fluoride-releasing device was due to topical effects of fluoride. Additional data suggest that the cariostatic effects of the intraoral fluoride-releasing device may persist for a significant time period after the device is removed from the mouth.